In the recent years, the micro laser thruster is the focus of the applied research of laser propulsion technology, which is aimed to apply in the task of pose and orbit control of the micro satellite. Based on the thermodynamic cycle analysis of the micro laser thruster engine, the effect factor on thermodynamic cycle efficiency is researched. The method of improving the propulsion performance is proposed, which is realized by changing the laser power density and target doping content. The regularity of the engine performance is verified by the experiment. The results indicate that the thermodynamic cycle efficiency is influenced by both laser and target, the pressure behind the shock wave could be increased by the increasing of laser power density, the specific impulse could be increased and the impulse coupling coefficient could be decreased; laser energy absorption could be intensified by the doped target, both specific impulse and impulse coupling coefficient are increased, and the thermodynamic cycle efficiency could be increased to some extent by the increasing of laser power density and target doping content.